The present invention relates to a continuously variable transmission to minimize a dynamic power loss through a gear mesh and to a method for engaging gears for a continuously variable transmission. Particularly, the present invention relates to a vehicle transmission, which has the continuously variable speed with an optimized transmission rate of dynamic power in a combustion engine.
A plurality of continuously variable transmission techniques have been proposed and these can be classified into mechanical, electrical and hydraulic methods.
A friction member, a belt or a chain has mechanically implemented the continuously variable transmission for vehicles. However, this mechanical transmission has several disadvantages as illustrated below.
First, in case where the friction is employed, power loss is caused by the power failure when the surface of the friction member is worn away and an alien substance is introduced thereto. Second, in case of the belt, if the tension of the belt is low, the slip is caused and, if the tension of the belt is high, overload is imposed on the belt and power loss is also caused by the introduce of an alien substance between a pulley and the belt, thereby forming the slip. Third, in case of the chain, the speed change is continuously achieved; however, a crashing sound is generated by a discontinuous contact between a pulley the chain and the increase of centrifugal force due to the weight of the chain makes maximum speed and large scale limited.
On the other hand, the techniques of the continuously variable transmission using the gear mesh are disclosed in Korean patent application Nos. 97-45324 (entitled, xe2x80x9ccontinuously variable transmissionxe2x80x9d), 97-58590 (entitled, xe2x80x9cvehicle transmissionxe2x80x9d) and 98-36378 (entitled, xe2x80x9ccontinuously variable transmission and vehicle transmission using the samexe2x80x9d) by Teak-Seo Goo, who is also the inventor of the present invention. However, these techniques have still limitations in power loss and cost because of a complicated gear mesh.
An object of the present invention is to provide a continuously variable transmission to minimize power loss through a gear mesh.
Another object of the present invention is to provide a vehicle transmission to minimize power loss through a gear mesh in a simple structure.
Also, another object of the present invention is to provide a method for meshing gears for a continuously variable transmission which is capable of controlling moving transporters forward and reward through a gear mesh.
In accordance with an aspect of the present invention, there is provided a continuously variable transmission in which a rotation power is transmitted with non-step from an input shaft to an output shaft, comprising: a) a carrier means engaged with said input shaft, wherein said carrier means rotates by a turbine shaft; b) a plurality of sets of planetary gears supported by said carrier means, wherein said planetary gear sets freely rotate in one body and wherein the number of teeth of one of said planetary gear set is smaller than that of the other of said planetary gear set; c) a first output means meshed with said planetary gears having the large number of teeth at an outside thereof; d) a second output means meshed with said planetary gears having the large number of teeth at an inside thereof; and e) a transmission means meshed with said planetary gears having the small number of teeth at an inside thereof and rotating by a subsidiary driving force in the same direction as said carrier means with a speed change, whereby a main driving force inputted into the input shaft is outputted with non-step through a gear mesh.
The input shaft is mechanically connected to said carrier means through a spline and the first output means includes: a ring gear meshed with said planetary gears having the large number of teeth at an outside thereof; and a forward clutch connecting said ring gear to said output shaft. The second output means includes: a reverse sun gear meshed with said planetary gears having the large number of teeth at an inside thereof; and a reverse clutch connecting said reverse sun gear to said output shaft. Also, the transmission means includes: a transmission sun gear meshed with said planetary gears having the small number of teeth at an inside thereof; and a hydraulic motor providing a subsidiary driving force to make said transmission sun gear rotate in the same direction as said carrier means or make said transmission sun gear rotate stop.
The transmission means is positioned between said input and output shafts in order that a speed change is achieved by a rotation speed of said hydraulic motor at a forward rotation of said first output means, and the transmission means is positioned between said input and output shafts in order that a constant speed is maintained through a stop of both said hydraulic motor and said transmission sun gear at a reverse rotation of said second output means. Further, the first output is engaged with said output shaft in order that a main driving force from said input shaft and a subsidiary driving force from said planetary gears combined with a change of speed.
The transmission sun gear is meshed with said planetary gears having the small number of teeth in order that said transmission sun gear rotates by both a rotation power which is caused by said planetary gears in the same direction and a rotation power which is caused by said hydraulic motor.
In accordance with another aspect of the present invention, there is provided a continuously variable transmission for a vehicle, wherein said vehicle comprising a power generation means, a hydraulic means, a wheel driving means, a control means to control said vehicle, said continuously variable transmission comprising: a) a carrier means engaged with a turbine shaft, wherein said carrier means rotates by said turbine shaft; b) a plurality of sets of planetary gears supported by said carrier means, wherein said planetary gear sets freely rotate in one body and wherein the number of teeth of one of said planetary gear set is smaller than that of the other of said planetary gear set; c) a first output means meshed with said planetary gears having the large number of teeth at an outside thereof; d) a second output means meshed with said planetary gears having the large number of teeth at an inside thereof; and e) a transmission means meshed with said planetary gears having the small number of teeth at an inside thereof and rotating in the same direction as said carrier means.
In accordance with still another aspect of the present invention, there is provided a method for meshing gears for a continuously variable transmission in which a rotation power is transmitted with non-step from an input shaft to an output shaft, the method comprising the steps of: a) engaging a carrier means with said input shaft, wherein said carrier means rotates by a turbine; b) providing a plurality of sets of planetary gears supported by said carrier means in order that said planetary gear sets freely rotate in one body, wherein the number of teeth of one of said planetary gear set is smaller than that of the other of said planetary gear set; c) providing a first output means meshed with said planetary gears having the large number of teeth at an outside thereof; d) providing a second output means meshed with said planetary gears having the large number of teeth at an inside thereof; and e) providing a transmission means meshed with said planetary gears having the small number of teeth at an inside thereof and rotating in the same direction as said carrier means.